Bubbler devices are widely used on automatic and semi-automatic watering systems for applying a metered uniform flow of water to the trees, shrubs, or garden beds in which they are installed. Typically, watering systems with which bubblers are employed incorporate a network of underground pipes, from which riser pipes extend at various positions where water is to be applied. The bubbler heads or bubbler devices are connected to the tops of these riser pipes. Typically the connection between the bubbler and the riser pipe is a threaded connection, so that the bubbler head may be removed or replaced when desired.
Typical bubblers are fabricated primarily of molded plastic parts and have relatively small passageways in them for controlling the flow of water under pressure in the riser pipe outwardly through the bubbler. These passageways frequently become plugged or clogged with particles of sand or other debris in the water supplied to the bubbler. To prevent clogging of the water passageways through bubblers, many bubblers employ an inverted cone-shaped filter screen at the bottom of the bubbler which extends into the riser pipe to trap or screen out particles of sand and other debris.
Although some bubblers are manufactured with no adjustment capability, the most widely accepted bubblers include a provision for adjusting the amount of water flow through the bubbler. This adjustment typically is from a full "off" position through an intermediate range to some maximum flow. The most popular forms of bubblers on the market today generally employ two or three plastic parts which are fitted together. In addition, a stainless steel adjustment screw interconnects the parts. This screw is adjusted either from inside the bubbler (which means the bubbler must be removed from the riser pipe to make the adjustment) or from a position through the top of the bubbler to effect the opening and closing of the passageways through the bubbler to control the water flow through it. Although the plastic parts are inexpensive, and the stainless steel adjustment screw also is inexpensive, the assembly requirements for interconnecting these parts comprise a substantial portion of the cost of the bubbler.
Efforts have been made to eliminate the stainless steel adjusting screw from bubbler devices. One such device is disclosed in the patent to Martin U.S. Pat. No. 2,723,879. This patent discloses a bubbler in the form of a three piece assembly. When the parts are interconnected together, water flow slots conduct the water from the riser pipe through the bubbler to distribution from beneath the cap of the bubbler. The cap of the Martin bubbler is internally threaded and fits over an externally threaded bottom portion. As a consequence, when the cap is screwed down to the closed position, water pressure within the cap tends to force it open; so that the parts need to be made relatively rigid to prevent leakage in the closed position of the bubbler.
Another attempt at simplification of a bubbler assembly by a reduction of parts is disclosed in the Patent to von Lutzow U.S. Pat. No. 4,159,805. This bubbler assembly is a two-piece plastic assembly. An extra manufacturing step, however, (or a more complicated mold) is necessary to provide radial passageways through the bubbler top to control the water flow. The nature of the radial passageways through the top of the von Lutzow device also limits the degree of adjustability of water flow which may be obtained from the bubbler. In addition, as with the device of the Martin patent, water pressure in the closed position tends to force the parts out of engagement with one another rather than into a tighter engagement; so that the parts must be made of relatively rigid material.
It is desirable to provide a simplified bubbler assembly, using a minimum number of parts, which is capable of simple and effective adjustment and which is not subject to the disadvantages of the prior art devices described above.